1. Field
Embodiment of the present invention generally relates to a method and apparatus for fabricating devices on a substrate. More particularly, embodiments of the present invention provide a substrate supporting ring to support a substrate around the edge region in a processing chamber.
2. Description of the Related Art
In the processing of substrates, such as semiconducting wafers and display panels, a substrate is placed on a support in a process chamber while suitable processing conditions are maintained in the process chamber. For example, a substrate can be heated in a controlled heating cycle to be thermally processed. During a thermal process, a substrate may be supported by a supporting structure, such as an edge ring, around the edge region while radiant energy source disposed above or below the substrate projects thermal energy towards the substrate.
FIG. 1A schematically illustrates a sectional view of a traditional edge ring 101 used in a thermal processing chamber. The edge ring 101 has an inner diameter slightly smaller than an outer diameter of a substrate 102 being processed. During processing, the substrate 102 is disposed on a supporting surface 105 of the edge ring 101 so that the edge ring 101 contacts and supports the substrate 102 by an outer edge region 104. Thermal energy 103 may be directed to the substrate 102 below the substrate 102 and the edge ring 101 to heat the substrate 102.
However, the traditional edge ring 101 as shown in FIG. 1A sometimes cause the temperature non-uniformity around the outer edge region 104 on the substrate 102. The temperature non-uniformity becomes more pronounced when the substrate 102 is heated at a rapid rate. FIG. 1B schematically illustrates temperature variations around the outer edge region 104 of a substrate during heating. In FIG. 1B, the x-axis indicates azimuthally locations in an outer edge of a substrate denoted by 0 to 360 degrees. The y-axis indicates a temperature variation from an average temperature in Celsius degrees. Each curve 110, 111 represents a measurement of a substrate during rapid heating. As shown in FIG. 1B, the temperature variation around the edge region of a substrate can be up to 8 degrees Celsius.
Therefore, there is a need for an improved substrate support for supporting a substrate around the edge region in a processing chamber.